The patent literature 1 discloses the following in-vehicle electric system. A first electric motor driving device and a second electric motor driving device are connected to a common DC power source. The first electric motor driving device drives a motor for running, and the second electric motor driving device drives a motor for an air conditioning device. A capacitor is connected in parallel with the DC power source. An LC filter is connected to a power source side of the second electric motor driving device. A resistor element is connected in series with a capacitor of the LC filter. When a frequency of a ripple current, outputted from the first electric motor driving device, overlaps with a resonance frequency of a π (pi) filter including C-L-C, the resistor element restricts an occurrence of resonance in the filter.